The present invention relates to a device for simultaneously tensioning a plurality of bolts connecting a first body to a second body with one end face of the first body abutting against a corresponding face of the second body, in which the bolts are axially immovably secured in the region of one of the ends thereof to the second body and project from the latter with clearance through bores in the first body and beyond the latter through corresponding bores in a carrier member arranged on a side of the first body facing away from the second body, in which at least one or a plurality of cylinders are arranged forming with a piston or pistons in the cylinder pressure spaces into which a hydraulic fluid under pressure is fed and in which the cylinders and the pistons therein apply, when hydraulic fluid under pressure is fed into the aforementioned pressure spaces, tension forces onto the bolts.
Such hydraulically operated tension devices are known from the U.S. Pat. No. 4,012,026. The constructions disclosed therein have, however, the decisive disadvantage that two separate tensioning steps and a changeover step has to be carried out in order to tension all of the bolts since in each tensioning step only half of the bolts are tensioned. The operation of these known tensioning devices is, therefore, time consuming and in addition there will not be produced a uniform tension in all of the bolts.
The German Gebrausmuster No. 70 21 273 further discloses a hydraulically operated tensioning device for simultaneously tensioning a plurality of bolts, tierods or similar elements, which comprises a carrier member consisting of an upper and a lower part and in which in the upper part for each of the bolts an annular cylinder is arranged which surrounds the respective bolt to produce a tension therein.
This known tensioning device has, however, the disadvantage that any difference in the efficiency of the individual cylinders acts in an unfavorable manner on the tension results so that the individual bolts may be tensioned in a slightly different manner from each other, whereby the difference may be of a magnitude of .+-.2.5% of the tensioning force. A further disadvantage of this known tensioning device is that it is rather expensive to produce.